linderpat

....and I don't mean the Pittsburgh Penguins, altho astonishingly that's where they find themselves in these playoffs.

This morning, fired up the car to drive it in. It has been stored for the winter, altho I have driven it sporadically as I always do when it is stored. Drove it most recently last Sunday for about a 10 mile loop.
Then and today, and every other time thru the winter, it fired right up. As always, idle starts high, but then settles in after a couple of minutes to a steady 750ish or so. Same thing this morning.
While waiting for it settle in on idle, I was re-setting radio stations then it just stopped. No chocking or coughing sounds, just one moment a steady idle and the next, nothing.
Tried cranking a few times. It has a good strong crank, but it doesn't catch.
Last thing done was a fuel filter replacement last fall before putting it up for the winter. The mechanic who did that for me in Montana said the old filter was very dirty. He also said that whenever he sees that, many times shortly after replacement the fuel pump dies. He said the reason is over time, because of the dirty and partially clogged filter, the pump has had to work harder, then after a replacement, and the sudden increase in volume, the pump simply can't handle it. This guy is an experienced Porsche guy, and has plenty of experience with 928's as well (there were surprisingly quite a few of them in Bozeman of all places!)

So, I am thinking easy stuff first - try to swap out the fuel pump relay, and then try to reverse flow as well and see if it is just clogged. If that doesn't work, then the next step would be to replace the fuel pump. Anybody know if there is one in the tank for this car? Mid-model '78 is the year. It is a CIS car too.

Anything else to check? The grounds were cleaned well last year.

911 Crazy

Any for sale up their? Have a meeting in MT in June.

WyattsRide

Give me a call if you want any assistance. If I'm available when you plan on working on it, I would like the opportunity to learn some things. I think you have my number.

I'm sure you'll get some good advice here. Good luck.

Alan

Listen to the pump to see if it sounds like its running first? (with FP jumper in place).

Sudden stop without any stumbling... that sounds more ignition like - final stage failure/coil would be an example - so I'd consider other options too... with spare plug see if you have spark? - quick even on both banks.

Alan

davek9

This is a '78 correct? No inside the Tank FP IIRC they did not start until the S4's to solve a Fuel heat issue in hot climates.
EDIT: also like Alan said, check the elect. bit's, relay, relay, relay and fuse's for clean and or hot spots on the contacts.

linderpat

Thanks Alan. I was hoping to not go down that path, but the sudden stop had me thinking electrical rather than mechanical. That makes it more complicated

Rick, I will let you know, but it won't be for awhile since the garage isn't set up yet and I am up to my @ss in setting up house.

911 Crazy - there is an outstanding 86.5 for sale there - my old one - here's the link. I wouldn't heesitate to buy this car, and if I had not moved, I would have bought it back.
Linky: https://rennlist.com/forums/vehicle-...ondition.html#

Alan

Just check for spark when cranking - use an extra plug - ground it with a booster cable (don't touch it). Not so hard.

Alan

Jadz928

Very close, Dave. In-tank pump started in '79. See below.

I'd start with the fuel pump fuse (#22?). Re: the relay, make sure you have the 5-prong FP relay.

Feel free to call for as needed armchair diagnosis.

linderpat

Thanks Jim. I forgot about that fuse.

linderpat

Alan - not sure what you mean by grounding it? What are the steps? I would have just pulled the boot off the front plug, stuck the extra plug in and touch it to something metal in the bay (away from fuel sources) and look for a spark. Should I do something else?
TIA.

davek9

Thanks Jim, then what years did not use them? I always thought they were used with the newer injection systems.

Mrmerlin

take wire with alligator clips and connect one to ground and the other side to the electrode,
then connect the plug wire to the plug crank and look for spark

Replace the fuel pump fuse

Alan

Yeah - don't touch it - sorry but your method is not at all good.

If you fail to actually ground it - YOU are the ground - and the 928 ignition system is quite capable of killing you - SO DONT DO IT!

Just use a nice solid conductor - I suggested one conductor of a booster cable to connect to ground and to the plug threads (since it has nice big croc clips) - then stay back and just watch it...no need to touch.

Alan

depami

Just curious, what makes the 928 ignition system so much more dangerous than any other?

whatudrivin

Likewise. I've been bitten a few times by spark plugs/wires. It can hurt. But I know it also has to do with how the current travels through your body and whether or not it gets to your heart.